drawbaugh



(No Model.) 4 Sheets-Sheet 1. D. DRAWBAUGH.

TELEPHONE TRANSMITTER. N0. 339,745. Patented Apr. 13, 1886.

WITNESSES JVVE-N TOR min) I IMMW, M22- 49 fim M rm,

(No Model.) I 4 Sheets-Sheet 2.

D DRAWBAUG-H TELEPHONE TRANSMITTER.

Patented Apr. 13, 1886.

WITNESSES D. DRAWBAUGH. LEPH NE TR Patented Apr. 13, 1886.

I VENTOR Jraw jvu D. DRAWBAUGH. TELEPHONE TRANSMITTER.

(No Model.) 4 Sheets-Sheet 4.

No. 339,745. Patented Apr. 13, 1886.

. INVEJVIOR Attcrneyaf UNITED STATES PATENT OFFICE.

DANIEL l)R.-\\VBAUGli, OF EBERLYS MILL, PENNSYLVANIA, ASSIGNOR TO TIIE PEOPLEK TELEPHONE COMPANY.

TELEPHONE-TRANSMlTTER.

SPECIFICATION forming part of Letters Patent No. 339,745, dated April 13,1886.

Application filed April 35, 1885!.

.To all whom, it may concern:

Be it known that l, DANIEL DRAWBAUUH, of Ebcrlys Mill. Cumberland county, Pena sylvania, have devised a new and useful Im- 5 provement in Telephone Transmitters, of

which the following is a specification.

The invent ion consists, in a telephone-trans mitter, of the combination of an elastic metallic diaphragm with a series of blocks of low I conducting material of particular form and arrangement; also, in the various devices, combinations, and sub-combinations and their practical equivalents as hereinafter set forth.

The object of the invention is to provide a i telephqnetransmitter of simple construction,

self-adjusting, not liable to break contact un der loud noises, or to get out of order, and at the same time sensitive and efficient in opcra- In the accompanying drawings, Figure 1 'is a front elevation of the instrument. Fig. 2 is the same with the cover of the box remove'd. Fig. 3 shows the rear side of the back board or base and the circuit-wires thereupon. Fig. 2 5 4 is a vertical longitudinal section on line 3/ 3 Fig. 1. Fig. 5 is a detail perspective view of the inside of the cover, showing the dampening-pad in position. Fig. 6 is a detail perspective view of the cylinder of low-conducting material. Fig. 7 is a detail perspective view of one of the inclined blocks of low-conducting material with itsbracket or holder.

Similar letters of reference indicate like parts.

A represents the base or back board, to which is secured the case B. having aeover, U, in which is formed the mouth-piece D. E is an elastic metal diaphragm tightly held by its edges between the cover 0 and case B. This diaphragm is therefore always under tension when in vibration, and does not move bodily under the influence of the sound-war es.

On the front side of the diaphragm E, oron that side against which speech is uttered, and

between said diaphragm and the rear side of the cover 0, I place a layer, 1 of cotton. felt, wool, or similar soft elastic material. This layer fills the space between cover 0 and dia- )hra m E and is held in 1- cc when the cover a l P Serial No. 510,492. (No model.)

is applied to the case and secured by the screws G. The object of the said layer is to weaken or destroy the false metallic vibrations of the diaphragu1,whieh mingle with the normal vibrations of the same due to speech uttered before it, and tend to produce a confusion of sounds in the receiving-telephone. I find that by the use of this dampening material with a tense diaphragm of metal I am enabled to obtain the sharpness and clearness of sound due to the metallic plate without its 5 disagreeable resonance, and thus greatly to improve the capability of the telephone in transmitting unaltered the quality of the voice.

To the rear side of the diaphragm E, and at or near its center, I attach, by solder or other 5 suitable means, a metal bracket, H, in which I place a block of .carbon or other low couductor. This 'block may be inclined or may have an inclined side, as shown in the drawings. Between the ends of this block and the bracket II, I place a layer, S, of any suitable insulating material, such as rubbcror paper.

To the back board, A, inside the case B, I attach a block, J, of carbon or other low-conducting material, similar in form to the block I, and held in a bracket, K, similar to the bracket H. The two blocks I and J have their inclined sides facing, so as nearly to form a V. The said blocks are, however, not in contact with each other.

Upon the inclined sides of the blocks I and J rests a third piece of low conducting mate rial, L, made preferably in cylindrical form. This piece L is in contact with both blocks I and J. it is prevented from falling out ofits 85 place between blocks I and J when the instrument is turned on its side or reversed by the bar M, which is suitably attached to the back board, A.

The circuits in this instrument are prefer- 9) ably led as follows: The local circuit, starting from the battery, enters the instrument at the binding-post N, proceeds thence by the wire a, (rear of back board) thence through the back board to the wire D, through the primary coil of the induction-coil O, and thence by the wire 0 to the bracket K; thence through the l0\\'-CO]lLlll(.'llI]g block J, cylindriral block L and block I, and bracket H to the metal diaphragm I The diaphragm, when in place upon the case, comes in contact with a. spring contact-piece, I, through which piece the circuit continues to th wire d through to the back of the instrumen then by the wire 0 to the binding-post N, and then to the battery.

The currents induced in the induction-coil O are taken to the main line bythc secondary wire of said, coil. Said secondary wire is shown leaving the coil at ff. The circuit passes through the back board, A, and proceeds by the wires g g to the binding-posts (3 Q, to which posts thc'linc and earth connections are made.

Branch wires h It extend down the rear side ofthe back board and connect with the 1 bindingposts It It, to which posts may be attached a receiving-telcplionc.

The operation ofthe instrument is as follows: The diaphragm in vibrating under the influence of sound-waves produced by the voice causes a greater or less compression of the low-comlucting blocks, thus modifying their resistance to and so varying and rendering undulatory the current passing through them. It will be seen that no matter how great the amplitude of the vibration thus caused of the diaphragm the contact between the cylinder I, and blocks I and J cannot be broken, for if the block I be moved toward the block .I the result is simply to lift the cylinder L to a higher position in the V formed by their inclined sides, while ifthe block I be moved from the block J the cylinder L descends to a lower position by its own gravity. No adjusting screws or springs are therefore necessary to maintain an initial pressure between the low-conducting pieces or to adjust the same, as said pieces are, in fact, self-adjusting.

I find that gas-carbon is preferably to be used as the substance for the low conducting blocks.

I am aware that before my invention thereof others had described the use in a telephone-transmitter of a sheet of soft elastic material entirely covering the exposed surface of the diaphragm hence said matter as described herein is hereby disclaimed.

Haying now described my invention, what I claim as new and original, and desire to se cure by Letters Patent. is-

1. In a telephone, the combination of an elastic vibrating metallic diaphragm with a block of low-conducting materialclosel y applied to its rear or inner side and substantially at its center, and with a second block of low-conducting material not in contact with the first block, the said two blocks being inclined to one another or having inclined faces placedrelatively opposite each other, andwith a loose block oflow-comlucting material which rests upon the opposite i ucliucd sides or faces of the two blocks aforesaid and is held in place and in contact upon them by gravity, substantially as described.

2. In a telephone, the combination of an elastic vibrating metallic diaphragm with a block of low-conducting material closely applied to the rear or inner side of said diaphragm and substantially at its center, and with a second block of lou=conducting material not in contact with the first block, and with a-loose block of low-conducting material which rests upon the two blocks aforesaid and is held in place and in contact upon them by gravity, substantially as described.

3. In a telephone, the combination of the metallic diaphragm E, the two supporting blocks I J, of low-conducting material, the cylinder L, of low-conducting material, resting on said blocks, the part] y-insulatcd brackets H and K for holding the blocks, and the bar M or its equivalent for preventing the cylinder falling out of place, substantially as de scribed.

4. The combination, substantially as here inbcfore set forth, of a tynipan or diaphragm connected with one of theterminals of an electric circuit,a bevcled,inclined,or tapering coir ductor mou ntcd on said diaphragnna similarly shaped conductor mounted on the box, case, or frame, and connected with the other terminal of the circuit, and an interposed conductor resting in sliding contact loosely upon the corre spondinglyshapcd portions of the supporting conductors, so that the strength of the current traversing the circuit may be charged by variations in the area of the points of the sur faces in contact in the degree of pressure exerted on the electrodes and in the length of the interposed. conductor traversed by the current.

5. The combination, substantially as here inbefore set forth, of a tympan or diaphragm constituting one terminal of an electric cir-' cuit, a semiconducting supporting-block mounted on said diaphragm and provided with a beveled, inclined, or tapering bearing or projection, a similar semi-comlucting supporting-block mounted on the box, case, or frame of the telephone and connected with the other terminal of the circuit, an interposed semi-conductor having its surfaces inclined and resting loosely upon the supporting-blocks .by gravity, and devices for retaining said interposcd conductor in position upon ,th supporting-blocks.

DANIEL DRAJVRAUGH. Witnesses:

\V. H. H. KNIGHT, EUGENE BAN'IA.

Correction in Letters Patent No. 339,745.

It is hereby certified that in Letters Patent No. 339,745, granted April 13,1886, upon the application of Daniel Drawbaugh, of Eberlys Mill, Pennsylvania, for an improvement in "Telephone-Transmitters, an error appears in the printed specification requiring correction as follows: In line 98, page 2, the word charged should be stricken out and'the Word changed inserted instead; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the came in the Patent Office.

Signed, ccuutersigned, anel sealed this 11th day of May, A. D. 1886.

H. L. MULDROW, Acting Secretary of the Interior.

[SEAL] Gountersigned M. V. MONTGOMERY,

Commissioner of Patents. 

